Electrolyte and method



Patented June 13, 1939 UNITED STATES PATENT OFFICE 2,162,391 MCTBOLYTE AND METHOD Donald E. Gray, Teancck, N. J.

No Drawing.

application July 6,1934,

Claims- M y i vention relates to electrolytic condensers and more particularly to electrolytic capacitors comprising one or more metallic foils or plates coated with oxide or dielectric fllm spaced from a second foil or plate by an electrolyte held by a carrier, such as a porous or other separator impregnated with an electrolyte solution.

This is a division oi! my co-pendin application Serial No. 733,976, filed July 6, 1934.

The general object of my invention consists in the provision oi. a novel me. trolytic condensers which is simple and easy to carry out and does not require highly trained and technical experience; as in the case o1 hitherto known methods in the art of manuiiicturing electrolytic condensers. 1

' A related object of my invention is to provide a novel method for more rapidly and economically preparing an electrolyte for electrolytic capacitors whereby no external heat need be applied,

enabling a cold impregnating electrolyte tor electrolytic condensers to be employed. V I 1 These and other objects and advantages of my invention will be apparent from the more detailed description-and explanation thereof which follows. It is to be understood that the descriptionis to be regarded as illustrative only oi-the general principle of the invention which is subject to various modifications and embodiments as will become obvious.

According to previously known methods; in order to iorm a compound-for impregnating an electrolytic condenser, it was customary to mix a suitable constituent, such as ammonium borate,

with a glycerine or glycol and boil the solution at certain critical temperatures in order to eliminate a certain amount of water, which method is very obiectionable and costly and has tobe care 1 fully watched as too much of the ammonia gas may be liberated by excess heating, thus making it diilicult to ascertain the exact and proper composition when the boiling is completed.

The novel method or preparing the electrolyte according to my invention consists in mixing (1) an anhydride or oxide of a weak acid, the anhydride being an oxide which combines with water to produce. an acid, as is well known; (2) an alkali metal hydroxide or ammonium hydroxideoranalkalimetaloxideorammonia,re-

5 spectively; and (3) a polyhydro xyl alcohol. The

anhydride or oxide of a weak acidioi group 1 may be boric oxide (Bios). I have found that for group 2 the lollowing oxides or hydroxides, respectively, give good results: sodium hydroxide or sodium oxide; ammonium hydroxide or amfor making electhe polyhydronl monia; potassium hydroxide or potassium oxide; calcium hydroxide or calcium oxide; strontium hydroxide or strontium oxide; lithium hydroxide or lithium oxide. For the polyhydroxyl alcohol of group 3 glycerin or ethylene glycol may be 5 used.

As an example, a simple method which I have found to give satisfactory and good results consists in mixing polyhydroxyl alcohol, such as ethylene glycol or glycerin (group 3) with am- 10 monia or an alkali oxide (group 2), thus making an alkaline glycerin or alkaline glycol solution, both of which give satisfactory results. Then to this mixture is added the desired quantity of the weak acid oxide, such as boric oxide (group is l), as mentioned above. The whole is thoroughly stirred to produce a certain desired, sticky, gummy-and paste-like mass oi thick consistency and structure to make the electrolyte. The boric oxide is obtainable in a powdered state, and when mixing with the ammoniated glycerin, or equivalent, as noted above, it is stirred, whereby a slight amount of heat is generated due to the chemical reaction and composition of the compounds. In

making this solution, no external heatis necessary to be applied as the solution is ready as soon as the mixing is complete, or,,ii it is desired to quicken the chemical action, a slight amount of heat can be applied.

While it is preferred add the alkali oi the electrolyte to the polyhydroxyl alcohol, this is v not required as good results can be obtained by mixing the oxide oi a weak acid (group 1) with alcohol (group 3), and then adding the alkali metal oxide or ammonia gas a (group 2) or the alkali metal oxide or ammonia (group 2) may be addedto the oxide ota weak acid (group 1), and the polyhydroxyl alcohol (group 3) then mixed.

The electrolyte can also satisfactorily be made 'by using nitrogenated polyhydronl alcohol such as triethanolamine or diethanolamine in which case it is unnecessary to use the alkali of group 2, for nitrogenated polyhydroxyl alcohol has 3 the alkaline reaction in itself. This electrolyte, 45 therefore, may be made with the nitrogenated polyhydroxyl alcohol and the oxide of a weak acid only.

I have also found it desirable in some cases to add a suitable thinning medium, such as water or a monohydroxyl alcohol to the above solution of electrolyte, or it is also possible to replace a I portion of the said weak acid oxide or alkali with the salt of a-weak acid or a weak acid itself.

I have iound it desirable, but not entirely necessary, in some cases, to add to the thus prepared electrolyte solution, various types of gum, such as gum tragacanth in order to produce certain desired characteristics in the electrolytic capacitor in which the electrolyte is used. The gum should be added to the electrolyte at a temperation and as described in detail herein are primarily intended for the impregnation of the assembled condenser; that is, to serve as a conducting medium or second condenser electrode, the other electrode being formed by the filmed foil with the dielectric or oxide film thereon acting as the condenser dielectric; it is understood that the electrolyte according to the invention may be used for producing the oxide or dielectric film on the positive conde'nser electrodes or foils by any treating methodknown in the art, such as an electrolytic process for producing a filmed electrode which is then assembled with another filmed or non-filmed electrode and impregnated with the operating electrolyte, according to the invention.

Electrolyte according to my invention can be used for both AC and DC'capacitors and with any type of spacers,-such as of paper, gauze or other fibrous ornon-fibrous material which is used for holding the electrolyte in capacitors; or

it may be used in some cases without a separator by placing a thin layerof the paste-like electrolyte on the electrodes.

I claim:

1. The method offorming an electrolytic solution for a metallic condenser foil which comprises mixing a polyhydroxyl alcohol with ammonia to make an alkaline alcohol solution, then adding a suitable quantity of weak acid oxide and thoroughly intermixing to produce a sticky paste-like mass'of comparatively thick consistency, the solution being applied continuously to the foil without artificial heat.

2. The method of forming an electrolytic solution for a metallic condenser foil which comprises mixing apolyhydroxyl alcohol with an alkali oxide to make an alkaline polyhydroxyl alcohol solution, then adding a suitable quantity of weak acid oxideand thoroughly intermixing to produce a sticky paste-like mass of comparatively thick consistency without evaporating water thereform.

3. The method of forming an electrolytic solu- I tion for a metallic condenser foil which comprises mixing'a polyhydroxyl alcohol with an alkali oxide to make analkaline polyhydroxyl alcohol solution, then adding a suitable quantity of weak acid oxide and thoroughly intermixing to produce a sticky pasteelike mass of comparatively thick consistency, the solution being app ied continuously to the foil without artificial heat.

4. A coated metallic foil for electrolytic condensers and thelike, the coating being of a thick paste-like consistency and applied to the ,foil, sa id coating comprising the product of a mixture of an anhydride of a weak acid, an alkali metal oxide and a polyhydroxyl alcohoL.

5. An electrolyte solution for electrolytic condensers which comprises the product of a mix-q ture of polyhydroxyl-alcohol with an alkaline compound selected from the group of oxides and hydroxides of sodium, potassium, lithium, calcium and strontium, said group also including ammonia and ammonium hydroxide, to produce an alkaline alcohol solution, and a suitable quantity of boric oxide thoroughly intermixed to secure a desiredconsist'ency of solution substantially without boiling.

7. An electrolyte for electrolytic condensers consisting of the product ofv a mixture of a polyhydroxyl alcohol, an alkali metal oxide or ammonia and a weak acid oxide in proportions to give substantially without boiling a consistency.

suitable for electrolytic condensers.

- 8. An electrolyte for electrolytic condensers consisting of the product of a mixture of polyhydroxyl alcohol, an alkali metal oxide or ammonia and boric oxide in proportions to give-substantially without boiling a consistency suitable for electrolytic condensers. I

9. An electrolyte for electrolytic condensers consisting of the product (i a mixture of a polyhydroxyl alcohol, a hydroxide of alkali metal or ammonia hydroxide and a weak acid oxide proportioned to give substantially without boiling a consistency suitable for electrolytic condensers.

10. An electrolyte for electrolytic condensers consisting of the product of a mixture of a polyhydroxyl alcohol, a hydroxide of alkali metal or ammonia and boric' oxide proportioned to give substantially without boiling a consistency suit- I able for electrolytic condensers.

11. An electrolyte for electrolytic condensers comprising the product of an intimate mixture of glycerine, ammonia gas and boric oxide.

12. An electrolyte .for electrolytic condensers comprising the product of an intimate mixture of ethylene glycol, ammonia gas and boric oxide.

13. An electrolyte for electrolytic condensers comprising the product of an intimate mixture of glycerine, ammonium hydroxide and borlc oxide.

14. An electrolyte for electrolytic condensers comprising the product of an intimate mixture of ethylene glycol, ammonium hydroxide and boric oxide.

15. An electrolyte solution for electrolytic condensers which comprises the product of a mixture of nitrogenated polyhydroxyl alcohol and a weak acid oxidethoroughly intermixed to secure the desired thick consistency of the solution substantially without the application of external heat.

16. An electrolyte solution ior electrolytic condensers which comprises the product of a mixture of ammoniated"polyhydroxyl alcohol and. a suitable quantity oi weak acid anhydride thoroughly, intermixed to secure a desired consistency of solution substantially without boiling.

17. An electrolyte solution for electrolytic condensers which comprises the product of a mixture of ammoniated glycerine and a suitable acidoxideinproportionsto oiweakacidanhydridethorouahly quantity termixedtosecurethe desired consistency o!- weak acid oxide, thoroughly intermixed to produce a sticky paste-like mass of comparatively thick consistency without boiling.

19. an electrolyte for electrolytic condensers oltheproductofamixtureotpolyhydroxyl alcohol, an alkaline material of the group conslsting of alkali metal oxides and ammonia. a weak acid and a weak acid oxide in proportions to provide substantially without boiling an electrolyte of suitable characteristics for electrolytic condensers.

20. An electrolyte ior electrolytic condensers consisting of the product of a mixture of polyhydroxyl alcohol, an alkaline material of the group consisting of alkali metal hydroxide and ammonia hydroxide, a weak acid and a weak provide mbstantlally without boiling an electrolyte oi. suitable characteristics for electrolytic condensers.

21. An electrolyte tor electrolytic condensers oitheproduotoiamixtureoinitrogenated polyhydronl alcohol, a weak acid and a weak acid oxide in proportionate providesubstantially without boiling an electrolyte of suitable characteristics for electrolytic condensers.

V trolyte oi. suitable 22. An electrolyte for electrolytic condensers consisting of the product of a mixture of polyhydroxyl alcohol, an alkaline material 0! the group consisting of alkali metal oxides and ammonia, a salt 0! weak acid and a weak acid oxide in proportions to provide substantially without boiling an electrolyte of suitable characteristics for electrolytic condensers. I A

23. An electrolyte i'or electrolytic condensers consist-ins oi the product of a mixture of poly-. hydronl alcohol, an alkaline material 0! the group consisting of alkali metal hydroxides and ammonia hydroxide, a salt of weak acid and a weak acid oxide in proportions to provide substantlally without boiling an electrolyte of suitable characteristics for electrolytic condensers.

24. An electrolyte for electrolytic condensers consisting of the product of a mixture 0! nitroaenated polyhydroxyl alcohol, a salt of weak acid and a weak acid oxide in proportions to provide substantially without boiling an eleccharacteristics for electrolytic condensers.

25. An electrolyte solution for electrolytic condensers which comprises the product or a mixture of po yhydroxyl alcohol, an alkalihe compound and a suitable quantity of weak acid anhydride thoroughly intermixed to produce an electrolyte having characteristics suitable for use in electrolytic condensers.

DONALD E. GRAY. 

